Drives That Do Not Need a Cabinet

ABB has released IP66/Type 4X-rated versions of its ACS580, ACH580 and ACQ580 drive families, announced on 3 September and aimed initially at Australian installations. The range covers 5.5 kW to 22 kW and ships with coated circuit boards for corrosive and humid atmospheres, integrated EMC C2 filtering, a built-in DC choke for harmonic mitigation, and Safe Torque Off as standard. Option slots take additional I/O and fieldbus modules, and Bluetooth control panels work with ABB's Drivetune mobile application. The target segments are food and beverage, HVACR, manufacturing, and water and wastewater. ABB's argument is economic rather than technical: a drive that can be mounted in the open removes the need for a protective enclosure or a dedicated electrical room.

The economics are worth taking seriously, because the drive is rarely the expensive part of a drive installation. An enclosure that has to be sized, ventilated or cooled, wall-mounted, wired to and from, and then maintained frequently costs more than the electronics inside it, and a dedicated electrical room costs a great deal more than that. Moving the drive to the motor also shortens the motor cable, which reduces both the voltage reflection that stresses motor insulation and the radiated emissions that long drive cables produce. In a washdown food plant or a remote pump station, the case is strong.

What deserves care is exactly what ABB itself flags in the announcement, and it is unusually candid for a product release: the IP66 rating relates specifically to protection against dust and water ingress, and is distinct from resistance to ultraviolet light and chemical attack. That distinction is the one most often collapsed in specification. A drive rated IP66 and installed outdoors in direct sun, or in an area cleaned with caustic or chlorinated agents, is protected against exactly one of the three things that will be attacking it. The coated boards address the internal corrosion question; the enclosure material and the cleaning regime are a separate conversation to have with the supplier.

Two other practical points follow from mounting a drive in the open. Heat has to leave through the enclosure wall rather than through forced ventilation, so the ambient temperature and any solar gain at the actual mounting position determine whether the drive derates — and a 22 kW drive in the sun is a different device from a 22 kW drive in a shaded plant room. And accessibility changes: a drive on the machine is exposed to impact, to washdown lances aimed at it, and to being used as a step, none of which appear in an ingress rating. For most installations the trade is still worth making; it is simply worth making with the mounting position chosen deliberately rather than wherever the cable happened to reach.